Electric heater with a sensor preventing no-water heating

Abstract

An electric heater with a sensor for preventing no-water heating includes a heating plate and/or a metal plate fixed on the heating plate, a heating film electro-plated on a lower surface of the heating plate, and a water level probe, or a sensing electrode, or a water level sensor and a temperature fuse fixed with the heating plate. The water level probe, the sensing electrode or the water level sensor produces alteration of electric potential in case of the water level becoming very low, triggering a switch of an A/D amplifying circuit automatically cutting off power of the heating film.

What is claimed is:  
     
       1. An electric heater with a sensor for preventing no-water heating comprising: 
       a heating plate provided with a vertical hole, having a heating film electroplated on a lower surface and two silver terminals fixed with said heating film for connecting with wires;  
       a water level probe fixed in said vertical hole of said heating plate for detecting water level of the water stored in a water tank on said heating plate, producing alteration of electric potential in case of sensing a very low water level, wherein said alteration of electric potential is fed to a control circuit, said control circuit then operates to automatically cut power off said electric heating film.  
     
     
       2. The electric heater with a sensor for preventing no-water heating as claimed in  claim 1 , wherein a metal plate is additionally provided on said heating plate. 
     
     
       3. An electric heater with a sensor for preventing no-water heating comprising: 
       a heating plate having a heating film electro-plated on a lower surface thereof and two silver terminals fixed with said heating film for connecting with wires;  
       a sensing electrode is provided on the lower surface of said heating plate for sensing water level of the water stored in a water tank on said heating plate, producing alteration of electric potential in case of sensing a very low water level wherein, said alteration of electric potential is fed to a control circuit, said control circuit then operates to automatically cut power off said electric heating film.  
     
     
       4. The electric heater with a sensor for preventing no-water heating as claimed in  claim 3 , wherein a metal plate is additionally provided on said heating plate. 
     
     
       5. An electric heater with a sensor for preventing no-water heating comprising: 
       a heating plate having a heating film electro-plated on a lower surface thereof and two silver terminals fixed with said heating film for connecting with wires, wherein the heating plate has a recess on the lower surface;  
       a water level sensor with and a temperature fuse provided in the recess on the lower surface of said heating plate for sensing water level of the water stored in a water tank on said heating plate, producing alteration of electric potential in case of sensing a very low water level, wherein said alteration of electric potential is fed to a control circuit, said control circuit then operates to automatically cut power off said electric, heating film.  
     
     
       6. The electric heater with a sensor for preventing no-water heating as claimed in  claim 5 , wherein a metal plate is additionally provided on said heating plate. 
     
     
       7. The electric heater with a sensor for preventing no-water heating as claimed in  claim 1 , wherein said heating plate is cylindrical. 
     
     
       8. The electric heater with a sensor for preventing no-water heating as claimed in  claim 1 , wherein said heating plate has a recess. 
     
     
       9. The electric heater with a sensor for preventing no-water heating as claimed in  claim 1 , said heating plate has a projection. 
     
     
       10. The electric heater with a sensor for preventing no-water heating as claimed in  claim 1 , wherein said control circuit includes an A/D amplifying circuit, which magnifies signals coming from said water level probe; and then sends the magnified signals to a switch, said switch automatically cuts off the power of said heating film when receiving the magnified signals.